The present invention relates generally to agricultural sprayers and more specifically to a folding spray boom assembly for such sprayers.
Agricultural sprayers having long, folding spray boom assemblies are well known and are capable of spraying very large areas in a short period of time. Typically, the folding boom assemblies are carried on a boom support frame on the sprayer vehicle and include an inner boom, and an outer boom which is hinged to the inner boom and can be pivoted about a generally vertical axis from the extended spraying position to a folded position for reducing the transport width of the sprayer. An upper support rod or cable or the like is tensioned between the outboard end of the inner boom and the boom support frame on the vehicle to support and stabilize the entire boom assembly in a substantially horizontal position above the ground. With this arrangement of the support rod or cable, the hinges connecting the booms must be strong enough to transfer the forces required from the outer to the inner boom to maintain the outer boom in a horizontal attitude. The length and weight of the outer boom, and jolting and rocking to which the boom assembly is subjected as the sprayer moves over rough terrain, results in a high amount of stress on the hinges.
A latch or retaining pin is required to hold the boom assembly in the unfolded or extended position. Often the operator has difficulty unfolding the outer boom to the exact position wherein the latch or pin can be operated or inserted to lock the boom in the extended position. Once the outer boom is locked in the extended position, it can no longer pivot away from an obstacle while the sprayer is in motion and the boom assembly can be easily damaged.
It is, therefore, an object of the present invention to provide an improved folding boom assembly for a sprayer.
It is another object of the present invention to provide an improved folding boom assembly for a sprayer wherein the stresses in the hinge area are reduced.
It is still another object of the present invention to provide a folding boom assembly with an improved support structure which reduces stresses in the assembly and which automatically holds the assembly in the extended position without need for a latch or retaining pin. It is another object to provide an assembly, which, when the operator wishes to lock to outer boom in the extended position, allows easy and quick locking without need to use force on the boom assembly to align the latch or pin.
It is still a further object of the invention to provide a folding boom assembly with an outer boom pivoted to an inner boom wherein the outer boom is free to pivot from the extended working position to avoid damage if it encounters an obstacle while being moved forwardly over a field.
It is yet another object of the invention to provide a folding boom assembly with a unique hinge and support arrangement which automatically biases the assembly toward the extended position when the boom is in or is approaching the extended position. It is a further object of the invention to provide such an assembly wherein the boom is biased toward the folded position when the boom is in or approaching the folded position.
It is still another object of the invention to provide an improved folding boom assembly wherein the upper tension link which supports the boom horizontally above the ground is advantageously utilized to both reduce stress in the hinge area between booms and to provide an overcenter arrangement which biases the outer boom toward the folded or unfolded position when the outer boom is in or is approaching the respective positions. It is a further object to provide such a boom assembly which will easily accommodate a hydraulic boom-folding mechanism.
In accordance with the above objects, an inner boom is connected to a support frame on a mobile sprayer and extends generally horizontally outwardly therefrom to an outermost end. An outer boom includes an inboard end hinged to the outermost end of the inner boom for swinging about an upright pivotal axis between an unfolded position wherein the booms are generally axially aligned, and a folded position wherein the booms are generally adjacent and parallel to each other. Hinge structure connecting the booms includes complementary inner and outer A-frames connected to the respective booms and having an adjacent pair of legs pivotally connected to define the upright pivotal axis forming an acute angle with respect to a transverse vertical plane. An upper elongated support rod is tensioned between the outer A-frame and the support frame to support the booms above the ground. The outer end of the rod is connected to the A-frame at a position radially offset from the axis so that the rod and hinge structure provide an overcenter device which acts to bias the outer boom to the final unfolded position as it approaches that position. Since the pivotal axis is angled with respect to the vertical, the end of the outer boom will be lifted as the outer boom is swung from its folded or unfolded position. This angle, as well as the radial offset provided between the rod connection and the pivotal axis, help determine the force necessary to move the outer boom from the folded or unfolded positions. Because the rod is connected to the outer boom, stresses across the hinge structure are reduced while the outer boom is unfolded. No latch or pin is necessary to hold the outer boom in either position as a result of the overcenter device.
These and other objects, features and advantages of the invention will become apparent from the description of the preferred embodiment which follows taken in connection with the accompanying drawings.